Intel CPUs are prone to hacker attacks after a vulnerability in the way they implement the SYSRET instruction was discovered in their x86-64 extension.

The vulnerability could allow hackers to execute code with kernel privileges while in a non-administrator account, or to gain control of a host operating system after escaping a virtual machine. The U.S. Computer Emergency Readiness Team (US-CERT) issued a security advisory in which it thoroughly details the vulnerability.

“Some 64-bit operating systems and virtualization software running on Intel CPU hardware are vulnerable to a local privilege escalation attack. The vulnerability may be exploited for local privilege escalation or a guest-to-host virtual machine escape,” says the US-CERT.

Several x64-based operating systems like Windows 7, Windows Server 2008 R2, 64-bit FreeBSD, 64-bit NetBSD, as well as systems that include the Xen hypervisor, are exposed to this vulnerability.

While 32-bit operating systems are safe, Intel CPUs that use the Intel 64 extension need the security patches released by Microsoft in their MS12-042 security bulletin.